The present invention relates to a probe for removing and sampling particulates in possibly corrosive gases in flues or chimneys. The probe is, in turn, connected with apparatus for measuring the state of the flue gas. See for example, European Patent Application 89 105 780.4, filed Apr. 1, 1989 and its corresponding U.S. application Ser. No. 503260, filed Apr. 2, 1990 now U.S. Pat. No. 5,033,318.
Such probes are known. They typically comprise four tubes of equal size arranged in a circle and spaced apart by spacing disks. They are surrounded jointly by a protective tube. The four tubes include pitot tubes which determine the difference pressure in the flue and therefore are used to measure the velocity of the flue gas and include a fresh air feed tube and a mixed gas removal tube. See the above noted application on how these tubes operate and cooperate.
The known probes have various disadvantages. They require a correspondingly large space for installation. Corrosive precipitates are produced in the probe due to the constantly varying dew point of the gases removed.